Low drift phase change material composite matrix

Abstract

A phase change memory device that includes a composite phase change material layer comprising a mixture of a dispersed phase of a projection material of a first resistivity, and a matrix of a phase-change material of a second resistivity or third resistivity dependent on phase. The first resistivity of the projection material has a resistance that is greater than the second resistance for the phase change material, and is less than the third resistance of the phase change material. The phase change memory device further includes a first electrode; and a second electrode on opposing faces of the composite phase change material layer. The projection material forms a percolated conducting path from the first electrode to the second electrode.

1 . A phase change memory device comprising:
 a composite phase change material layer comprising a mixture of a dispersed phase of a projection material of a first resistivity, and a matrix of a phase-change material of a second resistivity or third resistivity dependent on phase, wherein the first resistivity of the projection material has a resistance that is greater than the second resistance for the phase change material, and is less than the third resistance of the phase change material;   a first electrode; and   a second electrode on opposing faces of the composite phase change material layer, wherein the projection material forms a percolated conducting path from the first electrode to the second electrode.   
     
     
         2 . The phase change memory device of  claim 1 , wherein the second resistivity corresponds to a crystalline phase of the phase change memory, and the third resistivity corresponds to an amorphous phase of the phase change material. 
     
     
         3 . The phase change memory device of  claim 1 , wherein the projection material comprises a metal nitride, metal oxide, doped semiconductor, small bandgap semiconductor, topological insulator, topological semimetals, a Van der Waal material or a combination thereof. 
     
     
         4 . The phase change memory device of  claim 1 , wherein the projection material comprises a metal nitride selected from the group consisting of titanium nitride (TiN x ), tantalum nitride (TaN x ), tungsten nitride (WN x ), aluminum nitride (AlN x ) and combinations thereof. 
     
     
         5 . The phase change memory device of  claim 1 , wherein the projection material comprises a doped semiconductor selected from the group consisting of doped Si, doped SiGe, doped silicon carbide (SiC), doped germanium (Ge), and combinations thereof. 
     
     
         6 . The phase change memory device of  claim 1 , wherein the projection material is a small bandgap semiconductor selected from the group consisting of tin telluride, titanium telluride, gallium germanium, selenium, InSb, InAs, GaSb, AlSb and combinations thereof. 
     
     
         7 . The phase change memory device of  claim 1 , wherein the projection material is a semimetal selected from the group consisting of bismuth, tin (Sn), mercury telluride, graphite and combinations thereof. 
     
     
         8 . The phase change memory device of  claim 1 , wherein the projection material comprises a topological material selected from the group consisting of Bi 2 Se 3 , BiSb, BiSbTe, graphene, TaAs, WTe 2 , Na 3 Bi, Cd 3 As 2  and combinations thereof. 
     
     
         9 . The phase change memory device of  claim 1 , wherein the projection material comprises a Van der Waal material selected from the group consisting of WTe 2 , MoTe 2 , TiTe 2  and combinations thereof. 
     
     
         10 . The phase change memory device of  claim 2 , wherein the third resistivity of the amorphous phase is at least 20 times greater than that of the second resistivity of the crystalline phase. 
     
     
         11 . The phase change memory device of  claim 10 , wherein the electrical resistance of the percolated conducting path of the projection material has greater than 5 times more electrical resistance than percolated current path through the crystalline phase change material and has less electrical resistance than the resistance through the amorphous phase change material of the phase change material. 
     
     
         12 . The phase change memory device of  claim 1 , wherein the matrix of the phase-change material includes alternating layers of the phase change material with layers of conductive material. 
     
     
         13 . The phase change memory device of  claim 1 , wherein the matrix of the phase-change material includes alternating layers of the phase change material and dispersed phase of a projection material with layers entirely of the phase change material. 
     
     
         14 . The phase change memory device of  claim 1 , wherein the composition phase change material layer further comprises a non-conducting additive selected from the group consisting of Al 2 O 3 , Si 3 N 4 , SiO 2 , SiO, TiO 2 , HfO 2 , and combinations thereof. 
     
     
         15 . A phase change memory device comprising:
 a composite phase change material layer comprising a mixture of a dispersed phase of a projection material of a first resistivity, and a matrix of a phase-change material of a second resistivity or third resistivity dependent on phase, wherein the first resistivity of the projection material has a resistance that is greater than the second resistance for the phase change material, and is less than the third resistance of the phase change material;   a projection material layer in direct contact with a backside surface of the composite phase change material layer;   a backside electrode in direct contact with the projection material layer at the backside surface of the composite phase change material layer; and   a top electrode on an opposing face of the composite phase change material layer that is opposite the face of the composite phase change material layer that is in direct contact with the projection material layer, wherein the projection material forms a percolated conducting path from the first electrode to the second electrode.   
     
     
         16 . A method for reducing drift effects in a phase change memory device comprising:
 forming a composite phase change material layer comprising a mixture of a dispersed phase of a projection material of a first resistivity, and a matrix of a phase-change material of a second resistivity or third resistivity dependent on phase, wherein the first resistivity of the projection material has a resistance that is greater than the second resistance for the phase change material, and is less than the third resistance of the phase change material;   forming a first electrode and a second electrode on opposing faces of the composite phase change material layer; and   applying a current across the first and second electrode, wherein the projection material forms a percolated conducting path from the first electrode to the second electrode through a phase change region of the composite phase change material layer at one of the first and second electrode, wherein the projection material forms a percolated conducting path from the first electrode to the second electrode.   
     
     
         17 . The method of  claim 16 , wherein the forming of the composite phase change material layer comprises a co-sputtering method that employs a first sputter target to provide the phase-change material of the matrix of the phase-change material, and a second sputter target to provide the dispersed phase of a projection material. 
     
     
         18 . The method of  claim 16 , wherein the second resistivity corresponds to a crystalline phase of the phase change memory, and the third resistivity corresponds to an amorphous phase of the phase change material. 
     
     
         19 . The method of  claim 16 , wherein the projection material comprises a metal nitride, metal oxide, doped semiconductor, small bandgap semiconductor, topological insulator, topological semimetals, a Van der Waal material or a combination thereof. 
     
     
         20 . The method of  claim 18 , wherein the third resistivity of the amorphous phase is at least 20 times greater than that of the second resistivity of the crystalline phase.